Three Photon Decay of $J/\psi$ from Lattice QCD

TL;DR

This study calculates the rare three-photon decay rate of the $J/$ meson using lattice QCD with a novel method that directly relates correlation functions to the decay width, providing results consistent across two lattice spacings.

Contribution

The paper introduces a new lattice QCD method to compute the $J/$ three-photon decay rate directly from relevant correlation functions, improving accuracy for rare decay processes.

Findings

Decay rates: $(1.614 imes 10^{-5})$ and $(1.809 imes 10^{-5})$ for two ensembles.

Method to analyze Dalitz plot from lattice data.

Results consistent across different lattice spacings.

Abstract

Three photon decay rate of $J/\psi$ is studied using two $N_f=2$ twisted mass gauge ensembles with lattice spacings $a\simeq 0.085$ fm (I) and $0.067$ fm(II). Using a new method, only the correlation functions directly related to the physical decay width are computed with all polarizations of the initial and final states summed over. Our results for such rare decay on the two ensembles are: $\mathcal{B}_{I,II}(J/\psi\rightarrow 3\gamma)=(1.614 \pm 0.016 \pm 0.261)\times 10^{-5},(1.809 \pm 0.051 \pm 0.295)\times 10^{-5}$ where the first errors are statistical and the second are estimates from systematics. We also propose a method to analyze the Dalitz plot of the corresponding process based on the lattice data which can provide direct information for the experiments.